The present disclosure relates to sensing an arc within a gas insulated switchgear.
In general, a gas insulated switchgear (GIS) is a device for performing a switching operation in which a fault current may be interrupted as it occurs, including a circuit breaker, a disconnecting switch, an earthing switch, a current transformer, a bus, and the like, installed in a steel enclosure (or a metal casing) filled with SF6 gas having excellent insulating and arc-extinguishing characteristics. In the case that a fault current occurs, a circuit breaker in a GIS operates to break an electrical line and controls an arc generated at this time with the insulating gas.
When such a GIS is manufactured, transported, and assembled on-site, a conductor part therein may be damaged, a spacer may be cracked, a conductive foreign object, or the like, may be present therein, and these may cause an arc due to an insulation defect such as a short circuit in an electrical circuit. In particular, when a generated arc lasts for 100 ms or more, a system may be fatally damaged, and thus, an arc needs to be sensed in advance. In order to sense an arc generated within a GIS, an ultra-high frequency (UHF) sensor is largely used.
A UHF sensor relies on the principle that, when a partial discharge occurs within a GIS, a super high frequency (SHF) electromagnetic wave is leaked outwardly from the GIS. The UHF sensor may sense an internal arc by sensing an SHF electromagnetic wave leaked to outside. However, such a UHF sensor is commonly installed in a spacer outside of a GIS and may be relatively costly. In addition, a great deal of time and effort are required for post-processing calculations, such as translation of a sensed SHF signal in a frequency domain, and the like.